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Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel DeLucas, Marko Suput, Soobhankar Pati, and Uday Bhanu Pal Boston University

Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

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Page 1: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Magnesium Extraction From Magnesium Oxide Using Solid

Oxide Membrane Process

Rachel DeLucas, Marko Suput, Soobhankar Pati, and Uday Bhanu Pal

Boston University

Page 2: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Solid Oxide Membrane (SOM) Process for Magnesium Production-Leading to Magnesiothermic

Production of Other Metals

H2(g) + O2–(YSZ) →→→→ H2O(g) + 2e–

DC

Solid-Oxide Oxygen Ion Conducting Membrane(YSZ)

Anode

O2–(melt) →→→→ O2–

(YSZ)

Ionic Melt with Dissolved MgO

Mg2+(melt) + 2e– →→→→ Mg (g)

Cathode

CO(g) + O2–YSZ ���� CO2(g) + 2e–

V

O2–

O2–

Mg(g) + MeO = Me + MgO(s)

O2- →→→→ ½ O2(g) + 2e

Page 3: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Equivalent Circuit of SOM Cell

RRYSZYSZ(i(i)) RRfluxflux

(i(i)) RRmtmt EENernstNernst

RRYSZYSZ(e)(e) RRfluxflux

(e(e))

RRexternalexternalEEAppliedApplied IIcellcell

Rtotal = RYSZ (i) + Rflux

(i) + Rexternal + Rmt

EApplied - IcellRTotal = ENernst= (RT/4F) ln (PO2a/PO2

c)

Page 4: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Vertical Cross Section of the SOM Cell

Te

mp

era

ture

Page 5: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Experimental Setup

1 cm 3 cm

Page 6: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Potentiodynamic Sweep at 13000C

MgO Dissociation

0123456789

10

0 1 2 3 4 5

Applied Potential (Volts)

Cur

rent

(am

ps)

MgO Dissociation

Page 7: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

SOM Electrolysis of MgO

0

1

2

3

4

5

6

7

8

9

0 1 2 3 4 5 6

Time (hours)

Cur

rent

(A

mps

)Potentiostatic Hold at 4.0 Volts

MgO concentration is decreasing

1150 oC

Page 8: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

SOM Electrolysis of MgO20 KV scan( 2-4 micron penetration)

Energy (KeV)

0.0 0.5 1.0 1.5 2.0

CP

S

0

100

200

300

400

500

Mg

OC

Condensed Magnesium

Page 9: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Morphology of Magnesium Deposit

660 oC

530 oCCrystals

Lump

Page 10: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Stability of Membrane

100 µµµµm100 µµµµm100 µµµµm 100 µµµµm100 µµµµm100 µµµµm

a) As Receiveda) As Received b) Afterb) After ExperimentExperiment

••Membrane virtually unaffected after the 20 hour experimentMembrane virtually unaffected after the 20 hour experiment

••Selection of flux is critical to the processSelection of flux is critical to the process

••The operating life of Zirconia membrane will dominate overall cThe operating life of Zirconia membrane will dominate overall cost of ost of

the processthe process

Page 11: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

SOM design with single tube arrangement (100-200 g/day)

Page 12: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Cylinder Geometry 1-tube Model Current Density

Page 13: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

SOM Design With Triple Tube Arrangement (0.5-1kg/day)

Page 14: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Cylinder Geometry 3-tube Model Current Density

Page 15: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

3613464Electrolyte Capacity (g)

4.121.778Minimum Anode-Cathode Separation

Distance (cm)

364.8130.7Active Cathode Area (cm2)

15.245.461Crucible ID (cm)

91.230.4Active Anode Area(cm2)

155Total active anode length (cm)

31No of Anodes

Tubular COE Tubular COEAnode Structure

0.5-1 Kg/day 100-200 g/daySpecifications

SOM Reactor Design for Mg Production

Page 16: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Top and Side Views of the Possible Scale-up Version of the

SOM Electrolytic Cell.

Steel Cathode

SOM Anode

Mg Vapor

Page 17: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Comparison of the SOM Process Versus State-of-the-art Process for Electrolytic Production of Magnesium

SOM Process

MgO

Mg(OH)2 Kiln CalcinationMgO

Mg

H2O+CO2

Page 18: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

SOM Cell Physical Parameters

675-800 C1100-1150 COperating Temperature

Al2O3-SiO2MgO BasedRefractory

20-90 MT20 MTElectrolyte Capacity

Not Available290 cmCell Internal Diameter

3-6 cm4-8 cmAnode-Cathode Distance

Plate SteelPlate SteelCathode

0.5-100 kg/MT3-6 monthsHeat Anode Life/Consumption

Not Available185,900 cm2Anode Area

Not Applicable16 cmAnode Tube Diameter

100-120 cm100 cmWorking Length

Not Available37Number of Anodes

Chlorine and Chlorinated hydrocarbons

(CO, H2O or O2)By-Product Anode Gas

Graphite PlateTubular YSZAnode Structure

MgCl2MgOFeed Material

MgCl2 (1-4 MT/day)SOM (2 MT/day) Output

Page 19: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

SOM Cell Operating Parameter Comparison

0.25V0.25VContact and Leads

0.3V0.3 VCathode

10-1610-12Specific Power (k Whr/kg)

0.7 V0.7 VAnode

Not Applicable1.3 ViR drop (YSZ, 2mm thick)

1.3 V1-2 ViR drop (Electrolyte)

2.75 V0.82 VDissociation Potential

Potential Drops

4.5-7.2 V4.4-5.4 VCell Voltage

0.4-0.7 Amp/cm21 Amp/cm2Current Density

Output

MgCl2 (1-4 MT/day)SOM (2 MT/day)

Page 20: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Comparison of Projected Energy Balance

1,303,4833,947,340Total Heat Consumed

495,646700,500Heat Losses (Top Lid, Walls, Floor, Anode Heads)

14,01665,678Heat Loss Cell/Carrier Gas

10,418157,344Heat Escaping with Anode Gas

80,814---------Heat in Spent Electrolyte

22,175596,116Heat Escaping with Mg

9,12112,000Impurity Decomposition

671,2932,061,786MgO Decomposition

--------------353,916Heating of raw material

Energy Sinks

1,303,4833,947,340Total Sources

154,682------------Pre-Melted Feed Material

-----------379,070Chem. Energy-anode feed

1,148,8013,568,270DC Electrical Energy

MgCl2 (0.62 MT/day)

k J/hr

SOM (2 MT/day) k J/hr

Energy Sources

Page 21: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

SOM Features

• Cost Effective & Environmentally friendly– Direct reduction of Magnesium oxide– Minimize pre-processing, reduce capital and

operating cost

• High Current Density ( >1 Amp/cm2) � Good Scale up Potential

• Specific Energy consumption of MgO reduction is 10 KWh/Kg

Page 22: Magnesium Extraction From Magnesium Oxide Using Solid ...people.bu.edu/upal/pdf/SOM_Process.pdf · Magnesium Extraction From Magnesium Oxide Using Solid Oxide Membrane Process Rachel

Acknowledgements

Department of Energy

Boston University